A conventional in-wheel motor driving device 101 is disclosed in JP-A-2010-255713 (Patent Literature 1) for example.
The in-wheel motor driving device 101 which is presented in FIG. 10 includes a motor section 103 which rotatably drives an output shaft 106; a speed reducer section 105 which reduces rotation of the output shaft 106 and transmits the rotation to a wheel-side output shaft 108; and a wheel hub bearing section 104 which has a wheel hub 109 connected and fixed to the wheel-side output shaft 108.
As shown in FIG. 11, the in-wheel motor driving device 101 arranged as described above is designed so that the motor section 103 and the speed reducer section 105 are assembled independently from each other, and then a housing 107 of the speed reducer section 105 and a housing 102 of the motor section 103 are fastened to each other with bolts 110.
Also, in the example in FIG. 10 and FIG. 11, the wheel hub bearing section 104 has a fixing ring 111 (fixing member), which is fastened to the housing 107 of the speed reducer section 105 by using bolts 112.